Rectification towers



" Jan. 17,1967 I YOSHIJI MUTO ET AL r 3,298,673

RECTIFICATION TOWERS Filed May 8, 1964 Fla.

IN l/A'IW'ORS YosH/J/ Muro ATTORNEY 3,298,673 RECTIFICATION TOWERS Yoshiji Muto, Ibaragi-ken, and Takenori Hyugaji and Toshio Mihara, Hitachi-shi, Japan, assignors to Hitachi, Ltd., Tokyo, Japan, a corporation of Japan Filed May 8, 1964, Ser. No. 366,027 7 Claims priority, application Japan, May 9,1963,

5 Claims. (Cl. 261-22) This invention relates to an air separation apparatus United States Patent for separating air and recovering oxygen and nitrogen therefrom in a large quantity, and particularly to the use of a rectification column for separating air.

The rectification column, which is the main part of the air separation apparatus of the present invention, is conventionally utilized in the form of double columns consisting of a lower rectification column, a main condenser, and an upper rectification column. As is well known, liquid nitrogen of high purity is obtained in the lower rectification column, and in the upper rectification column, impure argon (contained in air in an amount of about 0.93%) is separated from oxygen to obtain oxygen of high purity.

Consequently, an argon-recovering column should be associated with a conventional rectification column for separating of argon from oxygen. Such an argon-recovering column has heretofore been positioned separately from the rectification column, outside thereof. Separate mounting of the rectification and argon-recovering column requires a relatively large amount of space as well as being expensive to construct.

The primary object of the present invention is to provide a rectification column of the kind specified with an argon-recovering column disposed within the rectification column in an appropriate position.

Other objects and particularities of the present invenvention will be made obvious from the following description and reference to the accompanying drawings, in which;

FIG. 1 is an elevational view diagrammatically showing a conventional double-type rectification column with a separate argon-recovering column, and

FIG. 2 is a similar elevational view, partly in longitudinal section, of a double-type rectification column embodying the present invention.

Referring to the conventional air separation apparatus of FIG. 1, an argon recovering column 2 is disposed outside a rectification column 1. The argon recovering column 2 is supported on a mount 4 which is secured to the rectification column 1, and the impure product containing argon separated in the rectification column 1 is withdrawn from the intermediate portion thereof by means of a pipe 3 and introduced into the argon-recovering column 2, where argon is removed. Such an arrangement naturally requires relatively large space as well as considerable material expense.

A conventional rectification column generally comprises an outer cylindrical easing, an inner cylindrical sleeve having a diameter of about one-third that of the outer casing, and a plurality of rectification plates mounted in multiple stages in the annular space formed by the outer casing and the inner sleeve which serves to reinforce the rectification plates. Needless, to say, in such a construction the inside space of the inner sleeve is not utilized resulting in a poor utilization of space.

According to the present invention, the inside space of the inner sleeve is fully utilized to accommodate the argon-recovering device therein.

Referring to FIG. 2, which is only exemplary of the present invention, the rectification column 1 is of the :1", a plurality of rectification plates 10 are disposed in multiple stages. An argon-recovering column 2, of the type knownin the art, is mounted inside of inner sleeve .1 and inserted through the top opening of the tower. The

bottom portion of argon-recovering .column 2.is connected by pipe 3 to the region of rectification column. 1 where the argon vapor occurs, usually at a temperature of about. 186 C. At this portion of the rectification column argon concentration is high-and nitrogen content is low. Air is, introduced into the bottomportionof. the lower rectification (highpressure zone) column by a'n inlet pipe 5, and they top portion of the lower column is connected bya pipe 6 to the top portionof the upper rectification column (low pressure zone). Liquid air is introduced into argon column 2 through an inlet pipe 7, and argon is drawn out through pipe 8. Argonrecovery column 2 and inner sleeve 1" of the rectification column are thermally insulated from each other by a heat insulator 9, so that the argon-recovery column itself performs conventional rectification similarly as has been achieved heretofore.

Air supplied from a regenerator, not shown, enters into the rectification column through the inlet pipe 5, and liquid air collects in the bottom portion of the column. The liquid nitrogen isolated therein in the upper portion of the lower column is fed to the top portion of the upper column through pipe 6. The upper column operates to rectify the three components, oxygen, argon, and nitrogen, in a well-known manner, and the argonrich gas is fed into argon column 2 through pipe 3. Liquid air is introduced into argon column 2 through the pipe 7 for cooling the argon-containing gas, the argon gas being thus separated therefrom by rectificatiin, and recovered through outlet pipe 8.

According to the present invention, the argon-recovering apparatus is disposed within' the inner sleeve of the rectification column, and thus does not require additional space for mounting, resulting in substantial savings in space and materials. The whole apparatus is relatively compact in size and light in weight, and contributes to the ready enlargement and increase in rated capacity of the apparatus.

What is claimed is:

1. A multilayer rectification column for separating air into oxygen, nitrogen, and argon which comprises a cylindrical casing composed of an upper and lower rectification zone, an inner cylindrical sleeve axially disposed in said cylindrical casing, the interior of said inner sleeve being hollow, a plurality of rectification plates mounted in multiple stages in the annular space formed by the cylindrical casing and the inner cylindrical sleeve, an argon-recovery column positioned inside the upper part of the hollow inner cylindrical sleeve, said argon-recovery column being thermally insulated from said sleeve by a heat-insulating material interposed therebetween, and means for communicating the lower portion of said argon-recovery column with the intermediate portion of the rectification zone where the argon concentration is high and the nitrogen content is low.

2. The rectification column of claim 1, wherein the argon-recovery column extends through the top of the cylindrical casing.

3. The rectification column of claim 1, including means for introducing air into the lower portion of the lower rectification zone, and means for communicating the upper portion of the lower rectification zone with the upper portion of the upper rectification zone.

' 4. The rectification column of claim 1, including means for introducing air into the argon-recovery column and drical casing composed of an upper and lower rectification zone, an inner cylindrical sleeve axially disposed in said cylindrical casing, the interior of said inner sleeve being hollow, a plurality of rectification plates mounted in multiple stages in the annular space formed by the cylindrical casing and the inner cylindrical sleeve, an argon-recovery column positioned inside the upper part of the hollow inner cylindrical sleeve, and extending through the top of the cylindrical casing, said argon-recovery column being thermally insulated from said sleeve by a heat-insulating material interposed therebetween, "means'for communicating the lower portion of saidargon-recovery column with the intermediate portion of the rectification zone, where argon'concentration is high and the nitrogen content is low, means for introducing air into the lower portion of the lower rectification zone, means for communicating the upper portion of the lower rectification zone with the upper portion of the upper rectification zone, means for introducing air into the argon-recovery column and means for withdrawing argon from said argon-recovery ,column.

I References Cited by the Examiner UNITED STATES PATENTS 1,619,909 3/1927 Wilkinson 6Z2Z 2,057,804 10/1936 Twomey 62-22 2,658,863 11/1953 Guala 2611 14 X 2,760,351 3/1956 Schilling 2611l4 X FOREIGN PATENTS 577,729 6/1959 Canada.

HARRY B, THORNTON, Primary Examiner.

20 RONALD R. WEAVER, Examiner. 

1. A MULTILAYER RECTIFICATION COLUMN FOR SEPARATING AIR INTO OXYGEN, NITROGEN, AND ARGON WHICH COMPRISES A CYLINDRICAL CASING COMPOSED OF AN UPPER AND LOWER RECTIFICATION ZONE, AN INNER CYLINDRICAL SLEEVE AXIALLY DISPOSED IN SAID CYLINDRICAL CASING, THE INTERIOR OF SAID INNER SLEEVE BEING HOLLOW, A PLURALITY OF RECTIFICATION PLATES MOUNTED IN MULTIPLE STAGES IN THE ANNULAR SPACE FORMED BY THE CYLINDRICAL CASING AND THE INNER CYLINDRICAL SLEEVE, AN ARGON-RECOVERY COLUMN POSITIONED INSIDE THE UPPER PART OF THE HOLLOW INNER CYLINDRICAL SLEEVE, SAID ARGON-RECOVERY COLUMN BEING THERMALLY INSULATED FROM SAID SLEEVE BY A HEAT-INSULATING MATERIAL INTERPOSED THEREBETWEEN, AND MEANS FOR COMMUNICATING THE LOWER PORTION OF SAID ARGON-RECOVERY COLUMN WITH THE INTERMEDIATE PORTION OF THE RECTIFICATION ZONE WHERE THE ARGON CONCENTRATION IS HIGH AND THE NITROGEN CONTENT IS LOW. 